The present invention relates to apparatus for removing successive lowermost sheets from a stack of superposed sheets, especially from a substantially vertical stack of sheets which can be converted into constituents of packs or analogous containers for cigarettes or other smokers' products. Typical examples of such sheets are revenue labels and blanks which latter can be converted into inner, intermediate or outer envelopes of various types of cigarette packs including those known as soft packs as well as the so-called flip-top or hinged-lid packs.
German Pat. No. 962, 869 discloses a method and apparatus for removing successive lowermost sheets from an upright stack or superposed sheets which are stored in a magazine. The patented apparatus includes means for flexing one or two marginal portions of the lowermost sheet away from the corresponding marginal portions of the next-to-the-lowermost sheet of the stack, and means for moving the thus deformed lowermost sheet sideways, i.e., at right angles to the longitudinal directions of deformed marginal portions. Such movement of the lowermost sheet, in a plane which is parallel to the plane of the next-to-the-lowermost sheet, does not present serious problems when the sheets are smooth. However, the just described method and apparatus cannot be used for removal of successive lowermost sheets from a stack wherein the sheets exhibit unevennesses, such as fold lines, notches, slits or the like, because neighboring sheets are likely to be interlaced with each other so that sidewise movement of the lowermost sheet often results in sidewise movement of one or more sheets thereabove. Examples of just discussed sheets are blanks which are made of stiff paper, lightweight cardboard or synthetic plastic sheet material and are to be converted into outer envelopes of flip-top packs. Such blanks are formed with longitudinally and transversely extending fold lines whereby the ridges at one side of one blank are likely to enter the grooves at the adjacent side of the neighboring blank. Also, those portions of the blanks which are formed with slits or notches are highly likely to become interlaced with similar portions of neighboring blanks. The situation is aggravated when the surrounding atmosphere contains a relatively high percentage of moisture; this causes the neighboring blanks to adhere to each other so that a sidewise movement of the lowermost blank of a stack of blanks invariably results in undersirable shifting or complete evacuation of the next-to-the-lowermost blank (or two or more blanks above the lowermost blank). Any shifting or premature evacuation of blanks which form the stack can entail lengthy interruptions in operation of the packing machine with attendant substantial losses in output.
Unrelated but equally serious problems arise in connection with removal of successive lowermost sheets which constitute revenue labels and are to be applied across the tops of successive cigarette packs. The labels are relatively small and narrow. Therefore, and since the labels are normally removed by shifting them lengthwise, the distance which the removing instrumentalities must cover in order to separate the lowermost label from the next-to-the-lowermost label is relatively long; this is undesirable because the intervals between removal of successive lowermost labels are also long. Sidewise shifting of labels is even less satisfactory because the labels are narrow and, therefore, the dimensions of removing devices must be reduced to a value at which such devices are incapable of securely grasping the labels during shifting out of register with the labels thereabove.